#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
int main()
{
    int task_1 = 0, task_2 = 0, task_3 = 0, task_4 = 0, task_5 = 0;
    float AVG = 0;
    scanf("%d %d %d %d %d", &task_1, &task_2, &task_3, &task_4, &task_5);
    AVG = (task_1 + task_2 + task_3 + task_4 + task_5) / 5.0;
    printf("%.1lf", AVG);
    return 0;
}